1. Field of the Invention
The invention is directed towards multi-dentate late transition metal polymerization catalyst complexes and their use in forming polymers from olefins or polar monomers and copolymers from olefins and polar monomers.
2. Description of the Related Art
Polymers and copolymers may be formed from olefinic monomers by using transition metal catalyst technology. Ziegler-Natta catalysts have been used for many years, while, in more recent years, metallocene catalysts have been preferred in certain applications, since the polyolefins produced via metallocene catalysis often possess superior properties. The most well known metallocene technology employs catalysts containing early transition metal atoms, such as Ti and Zr.
Even though polyolefins formed by such metallocene catalysts possess certain enhanced properties over polyolefins produced by conventional Ziegler-Natta catalysts, further improvements in properties such as wettability and adhesiveness may be possible. It is believed that including polar monomers in an olefinic polymer or copolymer would improve these, and possibly other, properties. Unfortunately, polar monomers tend to poison early transition metal catalysts.
Certain late transition metal complexes, such as those containing palladium and nickel, are more successful in incorporating certain polar monomers into polyolefins. However, most of these catalyst compositions are costly and produce highly branched polymers (e.g., 85-150 branches/1000 carbon atoms). Also, the functionalities are not in the chain, but at the ends of branches. Consequently, they are limited to polar monomer contents of about 15 mol % or less. Another disadvantage of these compositions is that they incorporate only a limited number of polar monomers, such as alkyl acrylates and vinyl ketones.
Recently, novel late transition organometallic catalysts have been made to address the aforementioned problems. More specifically, U.S. Pat. No. 6,037,297 to Stibrany et al., incorporated by reference herein, details group 11 (Cu, Ag and Au; new IUPAC notation) metal-containing catalyst compositions having a pseudotetrahedral geometry that are useful in forming polymers and copolymers having hydrocarbyl polar functionality. Other examples of group 11 metal-containing catalyst compositions are known. See, e.g., WO 98/35996 and JPA 11-171915, both to Shibayama, et al. and both incorporated by reference herein.
However, there is still a need to explore other group 11 metal complexes for use in polymerization processes. Ideally, these late transition metal complexes should be capable of forming olefinic polymers and copolymers containing polar monomers which are not highly branched, have polymer chain functionality and are capable of incorporating a wider variety of polar monomers.